The German Bight (North Sea) is a nursery area for both locally and externally produced sprat juveniles

To better understand the role of the German Bight (GB) as a nursery area for juvenile North Sea sprat Sprattus sprattus we sought to determine whether the area may receive only locally or also externally produced offspring. We sampled juveniles during 3 trawl surveys in the GB in August, September, and October 2004 and applied otolith microstructure analysis in order to reconstruct their distributions of the day-of-first-increment-formation (dif). These were contrasted with spatial and seasonal patterns of sprat egg abundance in the GB and its adjacent areas, observed during 6 monthly plankton surveys. It was found that the majority of juveniles originated mainly from April/May 2004, coinciding with high spawning activity west of the GB, whereas spawning and larval production inside the GB peaked notably later, in May/June. This indicated that a large proportion of juveniles was produced outside the GB and transported subsequently into it through passive and/or active migration. Shifts to later mean difs from one survey to the next and length distributions indicative of the simultaneous presence of multiple cohorts, supported the notion that the GB is a complex retention and nursery area for sprat offspring from different North Sea spawning grounds and times. Later born juveniles had significantly faster initial growth rates than earlier born conspecifics, which was likely temperature-mediated, given the strong correlation between back-calculated growth histories and sea surface temperature as a proxy for thermal histories of juveniles (r² = 0.52).     

2005年6月广东锋前暖区暴雨β中尺度系统特征的诊断与模拟研究

通过对雷达、卫星、地面等观测资料的诊断分析以及数值模拟研究, 对2005年6月广东 (粤中) 地区特大持续性暴雨的β中尺度系统进行了研究, 得出以下结果: (1) β中尺度系统是该次广东持续性暴雨的直接制造者, 当地的喇叭口地形非常有利于β中尺度系统的触发与维持。β中尺度系统发展初期有一些更小的γ中尺度系统的活动, 它们形成带状, 逐渐发展合并为β中尺度系统。 (2) 在较为成功的模拟的基础上, 采用模式输出资料对β中尺度对流雨团P作了仔细分析, 结果显示低层对应风场的辐合, 高层对应风场的辐散, 这种高低空散度场配置非常有利于强降水的产生和维持, β中尺度雨团中心对应着上升运动, 而在雨团北侧有弱下沉气流的补偿。引起降水的β中尺度系统多位于锋前暖区的相对更暖区域。 (3) 在同一次暴雨过程中, 粤桂两地同处锋前暖区, 对其风场上的异同点作了比较。共同点是低层均存在风场的辐合。但广西为风速辐合, 辐合中心具移动性, 而广东为风向辐合, 有明显辐合线, 辐合中心, 稳定少动。 (4) 地面辐合线上的扰动以及地面较强的温湿对比区的热力作用对于β中尺度系统的触发可能有重要的影响。地面资料提供了很有用的信息, 是一种重要的工具。 (5) 在此基础上提出了锋前暖区中尺度对流系统及地形、地面风、温、湿分布对其影响的概念模型。     

Improvement of TOPLATS‐based discharge predictions through assimilation of ERS‐based remotely sensed soil moisture values

In this paper, we investigate the possibility to improve discharge predictions from a lumped hydrological model through assimilation of remotely sensed soil moisture values. Therefore, an algorithm to estimate surface soil moisture values through active microwave remote sensing is developed, bypassing the need to collect in situ ground parameters. The algorithm to estimate soil moisture by use of radar data combines a physically based and an empirical back‐scatter model. This method estimates effective soil roughness parameters, and good estimates of surface soil moisture are provided for bare soils. These remotely sensed soil moisture values over bare soils are then assimilated into a hydrological model using the statistical correction method. The results suggest that it is possible to determine soil moisture values over bare soils from remote sensing observations without the need to collect ground truth data, and that there is potential to improve model‐based discharge predictions through assimilation of these remotely sensed soil moisture values. Copyright © 2002 John Wiley & Sons, Ltd.     

地形、冷池出流和暖湿空气相互作用造成北京一次局地强降水的观测分析

利用地面和探空常规探测资料、多普勒天气雷达以及风廓线雷达资料,对2015年8月7日发生于北京的一次伴随有闪电和冰雹的突发性局地强降水过程的成因进行了分析。结果表明:这次过程发生在强层结不稳定环境中,对流层中层低槽配合低层切变线,促进河北西北部对流发展,并向东南方向移动,形成北京西北部短时强降水;北京中部地区强降水的直接制造者则是新生的局地性雷暴单体,由雷暴冷池出流和暖湿空气在边界层交绥和辐合所触发。北京西北部地形促使冷池出流下山速度加快、冷池出流高度抬高,以及偏东暖湿气流的辐合抬升作用,则是局地雷暴新生的重要影响因子。     

2009年度大气科学领域项目评审与研究成果分析

1 2009年项目申请、送审与资助情况 2009年地球科学五处共受理各类项目768项(表1),其中,面上项目382项,青年科学基金254项,地区科学基金37项,上述3类项目共673项;"天气与气候系统变化过程与机制"优先发展领域重点项目18项(均为大气学科),"全球变化及其区域响应"优先发展领域重点项目41项(其中大气学科11项);国家杰出青年科学基金24项,海外及港澳学者合作研究基金5项,共计29项;创新研究群体科学基金3项;科学仪器专项基金3项;联合资助基金1项.     

New interferometric techniques for measuring horizontal earth crustal movements

An interferometer using modern interferometric techniques has been developed at ZIPE, which allows the measurement of distances of more than 1 km. The interferometric equipment was designed for comparing distances of different lengths and directions and is appropriate for testing horizontal earth crustal movements. The new interferometer is based on Michelson’s interferometer using collimated light. The interference fringes are received by means of photoelectric detectors and can be observed visually by an oscilloscope. The duration of an interference signal need be only 1 ms and the corresponding path difference is registered by printing. In order to get such interferograms, the path difference of the two beams is periodically changed within an effective range of 8 mm, whilst the total difference between the beams can reach an amount of 1 m. The interferometer has been tested on the Potsdam International Standard Base Line up to a distance of 2.7 km.     

The Implementation and Sustainability of Village Conservation Agreements Around Kerinci Seblat National Park,Indonesia

We investigated the implementation and sustainability of village conservation agreements and village conservation grants facilitated by an integrated conservation and development project (ICDP) around the Kerinci Seblat National Park, Sumatra, Indonesia, 5 years after the project closed. Forty-three percent of agreement actions (n = 180) and 30% of grant activities (n = 74) were sustained. Informants identified numerous factors influencing success, but statistical tests failed to detect simple explanations. Conservation-livelihood agreements have a greater chance of success when preexisting factors are understood and the purpose of the agreement itself is clearly defined.     

A budget analysis of a long-lived tropical mesoscale vortex over Hainan in October 2010

The vorticity, eddy kinetic energy, and helicity budgets were calculated to study the variations of a long-lived tropical mesoscale vortex that occurred over Hainan during the period 05?C09 October 2010. The main results are as follows: the vortex was mainly located at middle to lower levels of the troposphere, and among different levels, the dominant factors responsible for the variations of the vortex were different. Intense convergence at the lower troposphere dominated the formation and longevity of the vortex. The vertical transport of positive vorticity which was closely related to the convective activities was conducive to the formation and maintenance of the vortex. The barotropic energy conversion was favorable for the formation of the vortex, while the baroclinic energy conversion accelerated its attenuation. Background circulations were favorable for the longevity of the vortex, and interactions with other synoptic systems were important to its variations. The variation of helicity was closely related to the vortex, and the maintenance of positive helicity was another favorable factor for the longevity of the vortex.     

On the vorticity and energy budgets of the cold vortex in Northeast China: a case study

This study examines the vorticity budgets, turbulent extended exergy and kinetic energy evolution equations to investigate the major dynamical and energy conversion processes contributing to the initiation and intensification of the cold vortex over Northeast China that occurred during June 19–22, 2009. The results show that the cyclonic vorticity was initiated in the lower troposphere due to the intense convergence of horizontal winds. The growth of cyclonic vorticity in the middle troposphere is mainly due to the vertical transportation of the vorticity, yet the increase of cyclonic vorticity in the upper troposphere primarily results from the horizontal advection of vorticity. Of special interest in this study is the evaluation of the role of thermal advections in the baroclinic development of the cold vortex. The results indicate that the rising of the air over relatively warm areas and the sinking of the air in relatively cold regions are favorable for releasing turbulent extended exergy $ \left( {e_{\text{t}} } \right) $ , which is later converted to turbulent kinetic energy $ \left( {k_{\text{t}} } \right) $ , and this process occurs during the initiation and intensification of the cold vortex. In addition, barotropic energy conversion is another important process that contributes to the growth of k _t, and it strengthens gradually after the initiation of the cold vortex. Other than frictional consumption, the flux of k _t in the vertical direction also depletes some of k _t. The fluxes of e _t, baroclinic energy conversions and diabatic generations are favorable factors for the growth of e _t, whereas it decreases with time as a result of a large amount of e _t that is released. Most of the energy conversion processes, including the baroclinic and the barotropic energy transformations and the energy conversions from e _t to k _t, as well as the fluxes of e _t, are stronger in the lower troposphere than the other areas during the formation of the cold vortex. This accounts for the initiation of the cyclonic vorticity in the lower troposphere. Finally, the fact that the turbulent extended exergy releases primarily in the middle troposphere through the vertical thermal circulation is consistent with our understanding based on the vorticity budget analyses.     

Temporal cycles of karst denudation in northwest Georgia,U.S.A.

Time patterns of karst denudation in northwest Georgia (U.S.A.) were investigated at three spring sites for 12 months and at five stream sites for 10 years. Rainfall was evenly distributed and showed no significant seasonality. At the springs, as well as the streams, water hardness was largely controlled by discharge. At the springs, soil pCO₂ and water pH were strongly correlated (r + -0·69 to -0·83). Solute transport in spring waters was highly seasonal, with two conduit flow springs removing more limestone in the winter, and the diffuse flow spring removing more during the growing season. At the stream sites, most denudation occurred during the winter and spring seasons, and least during the summer. Fourier analysis showed that variations in denudation occur on deterministic (long-wave) as well as stochastic (shortwave) time scales. As contributing variables, discharge varied in short-wave and long-wave cycles, whereas soil pCO₂ showed only a long-wave cycle. The 12 month deterministic cycles were the most important, with changes in discharge taking precedence over soil pCO₂. Time series regression explains up to 69 per cent of changes in denudation through rain and soil pCO₂. Time cycles in available water are the key controlling factor of denudation, and amounts of available soil CO₂ may not be as important in the temporal patterns of karst downwearing as has been believed previously.